Newbie Question: Giving names to Elements of List/Tuple/Dict

[holger krekel]

Oren Tirosh wrote:
> On Sat, Nov 30, 2002 at 02:41:02PM +0100, holger krekel wrote:
> > > class record(dict):
> > >     def __init__(self, initfrom=(), **kw):
> > >         dict.__init__(self, initfrom)
> > 
> > But this pollutes the instance's namespace. 
> 
> Do you mean that dict methods without double-underscores? Yes, of you
> add a field called 'keys' to a record it will override the 'keys' 
> method inherited from dict. 

that's what i meant, yes.
 
> > Is inheriting from the dict class really neccessary?
> 
> Another way to achieve this effect is overloading __getattr__, __setattr__ 
> but it requires more code and is *much* slower.

just

    class record(object):
        def __init__(self, initfrom=(), **kw):
            self.__dict__ = dict(initfrom)
            self.__dict__.update(kw)

is *not* slower. 

But it doesn't offer item-access (__get/set/delitem__)
which is handy for non-string keys.  There you can use  getattr/setattr/
hasattr/delattr on a record instance.  If you really want to have the 
dictish methods then you could do 

            self.__getitem__ = self.__dict__.__getitem__
            self.__setitem__ = self.__dict__.__setitem__
            self.__delitem__ = self.__dict__.__delitem__

etc. in the __init__ constructor.  But I consider the dictish usage 
to be exceptional because otherwise you would use a dict anyway :-)

And for common (usual record/struct) usage

    r['name']  

is more noisy and less convenient than

    r.name

cheers,

    holger